1. Field of the Invention
The present invention relates to a processor controlled linear drive apparatus employed in automatic bonders and more particularly to a processor controlled Z drive motor for automatically positioning a wire bonding tool relative to the bonding pads of a semiconductor to be wire bonded at the first and second bond positions.
2. Description of the Prior Art
Automatic wire bonders have been made which have incorporated processor controlled X-Y tables coacting with the vertically moving bonding head. A bonding machine of this prior art type was made and sold by Kulicke & Soffa Industries, Inc. of Horsham, Pennsylvania as a Model 1412 Automatic Ball Bonder. The vertical movement of the bonding head of this prior art wire bonder was positioned by cams driven by a motor. The motor employed a dynamic braking apparatus and prior art positioning means for positioning the bonding tool.
Heretofore, numerical controlled machine tools were available which employed cutting heads capable of being positioned in more than three axes. The data stored in the memory of the processors of such prior art machine tools was provided by programmers working from drawings and encoding drafting tables of the type made and sold by Gerber Scientific Company of Connecticut.
Numerical controlled machine tools are known to have processor controlled cutting heads movable under controlled programs which would control the position of the cutting head in the Z axis or vertical direction. Such prior art program controlled machine tools have been driven through a first cutting operation to obtain data and to store the data in the memory of the processor so that identical subsequent cutting operations could be repeated. The usual means for driving the cutting heads of such prior art automatic machine tools are drive motors acting through relatively slow lead screws and are not suitable for positioning bonding heads of bonding machines.
Heretofore, fast acting lead screw drives have been employed in X-Y tables used on semiconductor bonding machines. Such X-Y tables have been made and sold by Kulicke & Soffa Industries Inc. in the aforementioned Model 1412 Automatic Ball Bonder. The high speed lead screw drives in such X-Y tables have been found to be too slow to obtain optimum speeds for driving a bonding head of a wire bonding machine.
It would be extremely desirable to provide a relatively inexpensive, reliable and extremely fast acting Z motor drive for positioning the bonding head of an automatic wire bonder.